Method for producing lubricating oil



Jan. 23, 1934.

("Lick 066 U. B. BRAY METHOD FOR PRODUCING LUBRICATING OIL OriginalFiled July 7, 1930 was INVENTOR Ulr ic .B. Bray 143 BY @flr .Zlea/ (J I06% ATTORNEY.

Patented Jan. 23, 1934 1,944,491 mz'rnoo roa rnog u cmc LUBBICATINGUlric B. Bray, Palos Vcrdos Estates, CaliL, as-

signor. to Union Oil Company 0! California,

Los Angeles; Calii., a corporation of California Original applicationJuly 7, 1930, Serial No. 466,189. Divided and this application January-10, 1933. Serial No. 650,994

14 Claims.

This invention relates to a method and apparatus for treating petroleumto produce lubricating oil and is a division of my patent applicationSerial No. 466,189, filed July 7, 1930.

It is an object of my invention to produce an asphalt and wax-freelubricating oil from an oil containing both asphalt and wax.

Briefly stated, my invention comprises a process for producinglubricating oil from an oil containing asphalt and wax by firstseparating the asphalt from the oil and wax and then separating the waxfrom the oil. One of the features of my invention resides in the use ofa solvent and in particular, a hydrocarbon solvent, for the purpose ofprecipitating the asphalt and dewaxing the oil. Another feature residesin the acid treatment and neutralization of the solution of oil, wax andsolvent subsequent to the step of separating the asphalt by means of thesolvent. Thus oil containing both asphalt and wax may be processed toproduce an asphalt and wax free lubrieating oil by mixing the oil with ahydrocarbon solvent capable of precipitating the asphalt but dissolvingthe oil and wax, the precipitated asphalt is separated from the solventsolution and the latter is chilled to precipitate the wax which is thenseparated from the oil solvent solution. The solvent may then beseparated by distillation. If desired, the solvent solution of wax andoil may be acid treated and neutralized prior to the dewaxing step. Thede-asphaltizing and chemical treatment steps may be effected under apressure above atmospheric.

More specifically, my invention comprises a process for separatingasphalt and wax from anlution from the precipitated asphalt while underpressure, in acid treating the propane solution under pressure andseparating the excess acid and products of reaction, in neutralizing theacid treated solution also under pressure, in separat ing theneutralizing reagent and the products of neutralization from the propanesolution, in releasing the pressure on the propane solution to effectvaporizationof a portion of the propane which in turn causes 'a chillingof the oil and consequent precipitation of the wax, in separating theprecipitated wax from the propane solution and finally, in separatingany unvaporized o residual propane from the oil, 7

Asphalt may be precipitated from oil by chemicals, such as sulfuricacid. I find, however, that it is best precipitated by use of solventsin which the lubricating oil fractions are soluble but in which theasphalt is insoluble. Such solvents are alcohol, ether, mixtures ofether and alcohol, acetone, volatilehydrocarbon solvents, such ascasing-head gasoline and light naphthas. I find, however, that theprocess is best carried out by the use of hydrocarbons which arenormally in the vapor state at atmospheric pressure and temperature.Such hydrocarbons include propane, isobutane, butane, ethane, methaneand mixtures thereof. These may be obtained by rectification ofcasinghead gasoline by the so-called stabilizing method now conventionalin the natural gas industry. They are the overhead thus obtained. Theyare liquefied by compression and cooling in the conventional manner anddrawn oil into pressure chambers where they are maintained in the liquidstate until they are used. A typical analysis of such a fraction is6.72% ethane, 72.20% propane, 19.91% isobutane and 1.17% normal butaneand the necessary pressure to maintain the fraction in a liquid state isapproximately 125 lbs. per square inch gauge at 73 F.

The oil stock containing asphalt is mixed with this liquid solvent underpressure, the mixture is allowed to settle to permit the precipitationof the asphalt. The solution or lubricating oil in the liquid solvent iswithdrawn from the pressure precipitator and expanded through heatingcoils to vaporize the solvent, leaving behind the liquid lubricating oilfree of asphalt. The vapors are recompressed and cooled to liquefy themand are then returned to the system. The lubricating oil fractionproduced may then be distilled at atmospheric pressure by conventionalmethods of distillation, such as the tube still or the shell still withproper rectification or fractionating equipment to produce any desiredcut of lubricating oil. Any contained wax may be extracted and the oiltreated with acid. I prefer to distill the oil to leave'a residue whichcontains the fractions having a viscosity above 400 to 500 secondsSaybolt Universal at 100 F. In other words, the degree of distillationshould leave a residue such that if it were redistilled the firstfractions taken overhead would be about 600 to 800 seconds SayboltUniversal at 100 F. These figures are by their very nature approximatesince they must overlap and the spread of the out will be dependent onoil may be more deeply topped, i. e., higher viscosity oils may betakenoverhead if a partial sacrifice of those desirable qualities is notuneconomic. It is to be noted that the above criteria will hold both forbatch and for flash distillation within reasonable commercial limits. Itis preferred to'top the crude so as to leave behind a residue which onextraction, as above, leaves a lubricating oil of the desired viscosity.However, the process may be run as well by topping the crude as far aspossible, extracting the residue .to remove the asphalt, treating thedistillate and residue with acids, alkali and/or clay and then blendingto the desired viscosity.

The following is a description of a preferred method for treating amixed base oh, i. e., one containing asphalt and wax, wherein theasphalt is precipitated under conditions such as to leave the wax andoil in the propane solution. Advantage is taken of the propane solutionto permit a continuous acid treatment and alkali treatment of the oil.This is a particular advantage of this process since it permits rapidsettling of the sludge. The extreme volatility of the propane is used toact as a refrigerant to cause separation of the wax. The process will bemore particularly described by reference to the drawing.

Referring to the drawing, the crude oil to be used as a source oflubricating oil is taken from the crude oilstorage tank 1 and sentthrough coil 2 in furnace 3, whence it is sent to evaporating column 4.The vapors passing through 5, consisting of gas oil, kerosene andgasoline vapors, go to dephlegmator 6 where they are fractionated intogasoline overhead and kerosene and gas oil bottoms, which may be re-runor handled in any conventional manner. The vapors pass through '7, arecondensed in 8, condensate, i. e.,

gasoline, is collected in 9. A part is returned through 10, todistributor 11, to act as a reflux. The dephlegmator bottoms passthrough 12, and

are cooled in 13. These consist of gas oil and.

kerosene. Part is returned as a wash via line 14 and spray 15. Thebottoms from evaporator 4,

consisting of oil containing lubricating fractions and asphalt, passthrough the rundown line 16 to the hot residuum storage tank 17 whichmay serve only as a surge tank in the continuous operation of theprocess. The hot residuum from tank 1'7 is passed through pump 18 whichsends the hot residuum through coil 19 in furnace 20, where the residuumis heated to about 625 F. Care is taken at this point not to overheatthe residuum because of the danger of injuring the quality of thelubricating oil to be obtained later. The temperature to which the oilmay be heated has been adequately described above. The heated residuumpasses to fractionating column 22.

* Steam, superheated in coil 21, is introduced in tionated byfractionating plates 23 and a number of $152 streams are removed throughlines 24 controlled by valves 25, reflux is generated by means of acooler positioned at the top of the column. The various oils passthrough valve 26 and are cooled in 2'7 and collected in 28. If desiredas many tanks as there are side streams may be employed. The side streamdistillates may be processed in any suitable manner to produce desirableproducts. The caverheads from the column pass through line 29, arecondensed in condenser 30 and cooled in rundown tank 31'. 'Uncondensedvapors are removed through 32, condensed oils composed of lightlubricating oilsare removed through 33 and the condensed water removedthrough 34. The bottoms from column 22 are run through line 35 by meansof pump 35a to cooler- 36"from which it is delivered to the toppedresiduum tank 37. The operation of coil 19 and column 22 is so regulatedas to produce the predetermined extent of topping necessary to give theproper viscosity oil in the later extraction with propane. The toppedresiduum stored in tank 3'7 is sent by pump 38, meets liquid propanecontaining a-small amount of oil comingthrough line 45. The preferredfraction is that obtained as an overhead in the stabilization of naturalgas gasoline as previously mentioned. The mixture of propane andresiduum pass through mixing coil 39 into decanter 40, where the asphaltin the topped residuum is precipitated and settles rapidly as a 'slurry.From the bottom of decanter 40, the asphalt slurry is pumped by pump 41to meet "fresh liquid propane introduced by pump 46 via line 47 frompropane storage 48. The asphalt slurry and fresh liquid propane are sentthrough mixing coil 42 into decanter 43. The asphalt propane slurry fromthe bottom of decanter 43 is drawn ofl through line 145, and valve 146and discharged at a lower pressure into a still, -as will be discussedhereafter.

The overflow from decanter 43, containing the oil and wax issent by pump44 through line 45 to be mixed with'the topped residuum and sent intodecanter 40, as explained above. The overflow from decanter 40consisting of propane and lubricating oil stock in the desired ratio issent through pump 51 for the acid and alkali treatment of the extractedlubricating oil stock. The countercurrent washing of the precipitatedasphalt illustrated by the above method 'of operation may be extended toas many steps as desired, but in general two decanters giving twocountercurrent washings will be sumcient to produce an asphaltsatisfactorily free of wax and oil.

To the propane solution. of extracted lubricating stock, acid fromtank52 is added to mixer 55 by means of pump (or acid egg) 53, and theflow is controlled also by valve 54. The propane solution and acid areforced by pumps 51 and 53 through mixing coil 55 into decanter 60 wherethe acid sludge settles rapidly. The addition of the acid in severaldumps without drawing the sludge between dumps may be accomplished bytapping mixing coil 55 at various points and introducing acid at thesepoints. The addition of acid in several dumps with the withdrawal ofsludge between dumps may be accomplished by means of additional'mixingcoils and acid decanters. The acid treated oil solution from decanter 60flows continuously through line 62 into decanter 63, where water isintroduced as a spray through line 68 from water storage 64 through pump65 and valve 6'7 and acid reaction products are withdrawn through line56'controlled by valve 5'7. The. water washed oil overflows fromdecanter 63 and is sent by pump- 69 to be treated. Water is withdrawnvia line 58 controlled by valve 59 The soda solution contained in tank'70 is introduced by pump '71 through line '72 controlled by valve'73.The mixture of oil solution and aqueous alkali solution is forcedthrough mixing coil '74 into decanter '75 where the caustic solutionseparates from the propane solution of the oil, and is withdrawn throughvalved line '76. 'The overflow from decanter '75 goes through line-77 todecanter '78, wheremater is introduced through spray 79 by, means of pum85 through valve 66. The separated water wash v as.

'94 until the predetermined quantity of solution is withdrawn throughvalved line 80. The use of propane as a solvent permits the continuousand rapid treatment of lubricating stockv in the manner Just described.

The neutralized and water washed oil solution overflowing from'decanter78 is carried by line 81 to tank 82, the latter acting as a reservoir orsurge drum between the acid treating and dewaxing operation. I

Treated oil solution in tank 82 is sent through valve 83 and line 84 toline 86 or 92 where it is sent into low pressure column87-or lowpressure column 94.by the proper operation of valves 85 and 93.Considering valves 91 and 93 closed and valves 85 and 90 open, thepropane solution flows into low pressure column 87. Valves 85 and 93 arepressure reducing valves separating the low pressure columns 87 and 94from the high pressure treating and decanting vessels. In low pressurecolumn 87, sufilcient propane vaporizes to reduce the temperature of theremaining material to a predetermined dewaxing temperature.

The desired dewaxing temperature is obtained by controlling the pressurein column 87 by the proper operation of valve 90 and propane compressor103, which is connected to the evaporatorby line 102. The pressure to bemaintained in column 87, as shown by gauge 89, will be, generally, about0 lb. gauge which corresponds to atemperature of approximately 40 F.

As the propane solution passes through valve 85, its pressure is reducedso that a portion of the propane evaporates in column 87 and the vaporspass out of the top, through mist extractor 87a through line 88controlled by valve 90. The solution from tank 82 continues to flow intocolumn 87 until a predetermined quantity has accumulated. Valves 85 and99 are then closed and valve 93 opened. Production then flows intocolumn has passed into the second column. The propane is vaporized,passes through mist extractor 95 through line 96, valve 98 beingcontrolled so that the proper reading is obtained on gauge 97. In

' the meantime, the vapor pressure of the propane in column 87 has beenreduced to approximately 0 lb. gauge by the operation of valve andpropane compressor 103, thereby reducing the temperature of the materialremaining in column 87 to approximately -40 F. When this temperature isreached in column 87, valve 91 is opened and the cooled materialispassed through line 100, pump 101 and valve 106 into the gas tightcentrifuge 107 in box-109. Motor 108 is for the centrifuge. Thecentrifuge is of conventional type. The dewaxed propane solution oflubricating oil discharged from the center of the centrifuge throughline 121 is sent by pump 122 through valved line 123 and heat exchanger124. In passing through heat exchanger 124, heat is absorbed from thevapors coming from the top of the evaporator 132. The propane solutionof dewaxed oil may be passed directly to evaporator 132 through line 128by the proper operation of valves 127 and 126 positioned in lines 125and 128. If it is desired to supply all or a portion of the heatrequired for vaporization of the propane by fire.

rather than by steam, the propane solution may be passed through coil129 in furnace 130 by the proper manipulation of valves 126, 127 and 131into evaporator 132. Open steam is introduced into evaporator through133 to complete the vaporization of the propane and to reduce the oil tosatisfactory flash and fire specifications. Injgeneral, however, thefunction of the steam will be to complete the vaporization of thepropane. The vapors passing through the mist extractor 134 pass from thetop of evaporator 132 through heat exchanger coil 135 where water iscondensed by the cold propane solution of lubricating oil coming fromthe centrifuge. Leaving heat exchanger coil 135, the condensed steam andany light oil removed from evaporator 132 pass into separator 138 withthe uncondensed propane vapors. The uncondensed propane vapors leave theseparator 138 through'line 139 and pass to line 40 from which they enterthe suction of propane compressor 144 to be compressed and sent throughline 104 to propane cooler 105 where the propane vapors are liquefiedand returned to propane-storage 48. Light lubricating'oil is removedthrough 138 and water removed through 137. The bottoms from evaporator132, consisting of'the treated and dewaxed oil, are drawn off by pump141 and passed through heat exchanger coil 142 where heat is imparted tothe water used to melt the wax in the wax discharge line from thecentrifuge, as will be later described. Leaving heat exchanger 142, thetreated and dewaxed oil passes into storage tank 143.

The wax discharged from the centrifuge F. The mel'ed wax and water passinto separator 111 and the wax is withdrawn through line 112 to waxstorage 113. The water from separator 111 is passed through line 114 towater storage tank 115 and then through line 116, pump117 and line 118to. heat exchanger coil 119 where it is healed by the bottoms fromevaporator 132, as explained above. The warm water-leaving heatexchanger coil 119 is passed through line 120 to line 110 to completethe cycle. The vapors from the top of separator 111, consisting ofpropane discharged with the wax from the centrifuge, are conserved bycompressing and returning to high pressure propane line 104 going i topropane cooler 105 bypassing through line 112a into line 140 andcompressor 144. The vapor space in the gas tight centrifuge should beconnected with the suction of a propane compressor discharging into thehigh pressure propane system. Provision for this latter conservation ofpropane is made by connecting either the dewaxed oil discharge line 121or the wax discharge line 110 with the gas space in the centrifuge, aswill be understood by those skilled in the art.

The asphalt material from separator 43 is passed through line 145,flashed through valve 146 and heating coil 147 in furnace 148 andpressure reduction valve 149 into evaporator 151, which operates at alower pressure. Steam superhea'ed in coil 150 is introduced into 151 tosupply additional heat and to reduce the asphalt to properspecifications, generally only as regards flash and fire points. Theasphaltis taken from the bottom of the evaporaior 151 and sent throughthe valved rundown line 159 to asphalt storage 160. The overhead fromevaporator 151 passing through mist extractor 152 is sent through line153, to cooler 154, and then to separator 155. The uncondensed propanefrom separator 155 is sent through line 157 to line 140 to ihe suctionof pro-' pane compressor 144 where its pressure is raised to that in thehigh pressure system and then sent to line 104 to propane cooler 105where it liquefles and runs down into propane storage tank 48. Anycondensed light oil is withdrawn through line 156 and condensed waterthrough line 158.

(iii

From the standpoint of convenience and operation, it may be desirable toconnect all of the high pressure vessels containing liquid propane to apressure equalizing line 49 controlled by valve 50, as shown in thedrawing. Without provision for equalizing the pressure in the difierentvessels, flow of liquid will be controlledentirely by pump pressure. e

In the operationof the centrifuges, it is desirable to maintain a higherpressure upon the-propane, oil, wax mixture than corresponds to thevapor pressure of the mixture at that temperature. The reason for thisincreased pressure is to prevent foaming or gas evolution in the liquid.This pressure is applied by p ump 101. If it is desirable to operate thecentrifuge at atmospheric pressure or at only slightly increasedpressure, the pressure maintained in cooling column 87 or 94 before theliquid in that column is sent to the centrifuge should be less thanatmospheric pressure, so that when the pressure is raised to atmosphericbefore passage through the cenrifuge, the liquid may warm up severaldegrees without "boiling or foaming.

Evaporator 132 may be operated at a suificient- 1y high pressure tocause liquefaction of the propane vapors when cooled, and in this mannereliminate theuse of a compressor on the vapors from the top of separator136. When operating column 132 at high pressure, pump 122 is operated ata higher discharge pressure and heat exchanger 124 is operated so as tocause condensation of only steam and oil vapors.

The above description is merely illustrative of one mode of employing myinvention and is not to be construed-as limiting as many variations willappear to those skilled in the art within the scope of my inventionwhich I claim to be:

1. A method for the production of lubricating oil from oil containingasphalt and wax which comprises mixing the oil with a volatile solventunder superatmospheric pressure to dissolve the oil and wax and toseparate asphalt, separating the asphalt from the oil wax solution,releasing the pressure on said solution to evaporate the solvent andcool the oil to precipitate the wax, separating the wax from the cooledoil.

2. A process for the production of lubricaing oil from oil containingasphalt and wax which comprises commingling said oil in liquid propaneunder superatmospheric pressure to dissolve the oil and wax and separateasphalt, separating the undissolved asphalt from the propane solution ofoil and wax, releasing the pressure and vaporizing a portion of theliquid propane to cool the propane solution of oil. and wax to atemperature sufficiently low to precipitate the wax, separating theprecipitated wax from the oil dissolved in the remaining propane andsubsequently separating the remaining propane from the oil.

3. A method of producing lubricating oil from oil containing asphalt andwax which comprises contacting said oil with a hydrocarbon solvent undersuperatmospheric pressure to precipitate asphalt, separating theprecipitated asphalt from the oil, treating the oil solvent solutionwith acid, releasing the pressure on the oil solvent solution andvaporizing a portion of said solvent to cool the oil and precipitate thewax, separating the precipitated wax from the cooled oil solventsolution and then separating the residual solvent from the oil. 5

' 4. A process for the production of lubricating oil from an oilcontaining asphalt and wax which comprises mixing said oil with liquidpropane under superatmospheric pressure, separating undissolved asphaltfrom the solution of oil, wax and liquid propane, treating the oilsolvent solution with acid, separating the oil solvent solution fromacid and acid reaction products, treating the oil solvent solution witha neutralizing agent, separating the oil solvent solution from saidneutralizing agent and the products of neutralization, cooling thepropane solution of oil and wax to a temperature sufllciently low toprecipitate the wax by vaporizing a portion of said propane underreduced pressure, separating the precipitated wax from the oil dissolvedin the remaining liquid propane and subsequently separating the oil fromthe remaining propane.

5. A method of producing lubricating oil from an oil containing asphaltand wax which comprises treating the oil with a solvent, dissolving theoil and wax and separating the undissolved asphalt, partiallyevaporating the solvent from the oil solvent solution to chill theresultant oil and precipitate wax, separating the wax and thendistilling off the residue of solvent from the oil.

6. A method for the separation of asphalt and wax from oilwhichcomprises extracting said oil with a normally gaseous liquid hydrocarbonsolvent consisting of a major proportion of hydrocarbons of less thanfour carbon atoms to cause a separation of the asphalt, separating theasphalt from the oil and wax dissolved in said hydrocarbon solvent,chilling said hydrocarbon solvent solution of oil and wax to precipitatewax and separating the precipitated wax from the oil dissolved in saidhydrocarbon solvent.

7. A method for the separation of asphalt and wax from oil whichcomprises extracting said oil with a normally gaseous hydrocarbonsolvent consisting of a major proportion of hydrocarbons of less thanfour carbon atoms to cause a separation of the asphalt, separating theasphalt from the oil and wax dissolved in said hydrocarbon solvent,vaporizing a portion of said hydrocarbon solvent from the solventsolution of oil and wax to chill the oil and precipitate wax andseparating the precipitated wax from the oil and remaining solvent.

8. A process for the separation of asphalt and wax from oil whichcomprises commingling said oil with a normally gaseous hydrocarbon undersuperatmospheric pressure suflicient to maintain said hydrocarbon liquidand at a temperature sufllciently elevated to dissolve the oil and waxin said hydrocarbon solvent and to separate asphalt, separating the oiland wax dissolved in said hydrocarbon solvent from the separatedasphalt, chilling the hydrocarbon solution of oil and wax to precipitatewax and separating the precipitated wax from the oil dissolved in said 135 hydrocarbon solvent.

9. A process for separating asphalt and wax from oil which comprisescommingling said oil with a normally gaseous hydrocarbon undersuperatmospheric pressure sufl'icient to maintain said hydrocarbonliquid and at a temperature sufficiently elevated to dissolve the oiland wax in said hydrocarbon solvent and to separate asphalt, separatingthe oil and wax dissolved in said hydrocarbon solvent from the separatedasphalt, releasing the pressure and vaporizing a portion of thehydrocarbon solvent to cool the oil and precipitate wax and separatingthe precipitated wax from the oil and remaining hydrocarbon solvent.

10 A process for separating asphalt and wax from oil which comprisescommingling said oil with a normally gaseous hydrocarbon, the majorportion of'which consists of propane and ethane and undersuperatmospheric pressure sufllcient to maintain said hydrocarbonsolvent liquid and at a temperature sufilciently elevated to dissolvethe oil and wax in said hydrocarbon solvent and to separate asphalt,separating the oil and wax dissolved in said hydrocarbon solventfrom-the separated asphalt, chilling the hydrocarbon solvent solution ofoil and wax to precipitate wax and separating the oil dissolved in saidhydrocarbon solvent from the precipitated wax.

11. A process for the separation of asphalt and wax from oil whichcomprises commingling said oil with a normally gaseous hydrocarbon, themajor portion of which consists of propane and ethane, and undersuperatmospheric pressure suflicient to maintain said hydrocarbonsolvent liquid and at a temperature sufilciently elevated to dissolvethe oil and wax in said hydrocarbon solvent and to separate asphalt,separating the oil and wax dissolved in said hydrocarbon solvent fromoil which comprises extracting said oil with a liquid hydrocarbonsolvent, the major portion of which is propane to separate asphalt,separating the asphalt from the oil and wax dissolved in saidhydrocarbon solvent, chilling the hydrocarbon solvent solution of oiland wax to precipitate wax and separating the precipitated wax from theoil and hydrocarbon solvent.

13. A method for separating asphalt and wax from oil which comprisesextracting said oil with a liquid hydrocarbon solvent, the majorportion, of which is propane to separate asphalt, separating the asphaltfrom the oil and wax dissolved in said hydrocarbon solvent, vaporizing aportion of said solvent to chill the oil and precipitate wax andseparating the precipitated wax from the oil and remaining solvent.

.14. A method of producing lubricating oil from III

